1. Field of the Invention:
This invention relates to an adjustable vibration damper, in particular for motor vehicles, with a cylinder containing a damping fluid, an axially-movable piston rod projecting into the cylinder in a sealed manner, and a damping piston fastened to the piston rod, which piston divides the cylinder into two work chambers, whereby a damping valve with an axially-movable valve body and a valve seat controls the effective cross section of a damping passage.
2. Description of the Prior Art:
The prior art includes hydraulic, adjustable dampers, e.g., German Laid Open Patent Application No. DE-OS 21 19 531, in which there is a first damping element plus a line equipped with a regulating valve. In a closed loop, always separately, are a regulating valve and a damping element. The adjustment of the regulating valve is done manually or by the action of one of the vehicle mechanisms. A disadvantage with this type of damper is that it is difficult to manufacture on account of the inclusion of a line and components located in series. Moreover, the mechanical activation produces a certain damping force, and with different damping force characteristics, variability is impossible to achieve. The prior art also includes hydraulic vibration dampers, e.g., German Patent Publication Published for Opposition Purposes No. DE-AS 12 42 945, whose damping characteristic can be electromagnetically regulated by changing the flow of the hydraulic damping medium through the damping valves. In such a case, there is a bypass connection, in which a damping valve controls a spring loaded valve body, so that the damping force in the decompression stage can be regulated in relation to the compression stage. The valve body is thereby held either in the open or the closed position by means of the electromagnet. Each of the above-mentioned patents are incorporated by reference as if the entire contents thereof were fully set forth herein.